Overhead electric wires are usually carried by porcelain insulators which are maintained upright by an upstanding pin engaging an axial blind bore of the insulator body, the pin fixed to the cross-arm of a pole or tower. The insulator has a saddle-like upper portion which receives and supports the electric wire. The latter is attached to the insulator by the tricky operation of manually winding and twisting a small-diameter tie wire around the electric transmission wire and a waist portion at the base of the insulator saddle portion. In applicant's U.S. Pat. No. 4,810,837, issued Mar. 7, 1989 and entitled: "CLASP FOR FIXING AN ELECTRICAL WIRE TO AN INSULATOR AND METHOD OF FIXATION", there is described a novel clasp which considerably facilitates attachment of the electrical wire to the insulator. This clasp includes a metallic clamp and an elastomeric wire-gripping element carried inside the clamp for surrounding and being pressed against the wire for firmly retaining the latter against longitudinal slipping. The clamp itself is a metal piece forming a central top web, with lateral downwardly-extending arms, in turn provided with inturned lower flanges, each having an inner partly-circular recess. Conventional insulators have a lower bell shaped portion and a saddle portion. The saddle portion includes a transverse electric wire-receiving groove and jutting parts on each side of the groove. The external surface of each jutting part includes side face portion, which is downwardly, inwardly inclined and which smoothly merges with the top of the bell-shaped portion at a narrowest waist area between the top saddle portion and the lower bell-shaped portion. Therefore, when using the clasp of U.S. Pat. 4,810,837 on a conventional insulator of the type above described, it was found that the clamp can detach from the insulator under certain circumstances circumvented by the present invention.